Emission mechanisms in quasars part 2: radio loud quasars and BL Lac objects

scientific abstract most objects with cosmological redshift (z > 0.5) have been found by means of their radio emission (radio loud quasars and radio galaxies) or due to their optical emission lines (radio quiet quasars). very little is known about the fir spectra of these objects since iras could obtain spectra only for the 50 brightest members of this class. on the other hand, it is just the range between 20 and 200 microns where one expects the thermal emission to overrun the nonthermal radiation dominating the radio regime. thus fir spectra should show both the shortest wavelengths of nonthermal and the longest wavelengths of thermal continuum emission which are of great importance for a theoretical understanding of the various emission pro cesses and their origin in the cores of agns. we propose to measure the spectrum of several carefully selected quasar samples between 5 and 200 microns with isophotp and isophotc in order to identify the different components. this will be done by quasisimultaneous multiband photometry. polarization and variability studies which can even clearer distinguish between synchrotron and other components will be performed for a few key objects. evolutionary trends will be investigated by measuring quasars in the redshift range between 0.1 and 4.5. observations of a sample of radio gal axies from the 3ccatalogue will test whether the unified schemes are viable which interpret radio galaxies as quasars seen under distinct angles. the total spacecraft time of the proposal is 35 hours with a mean observing efficiency of 45 %. observation summary the continuum emission of quasars between 4.8 and 200 microns will be traced with isophotp in six filters (p_4.85, p_7.3, p_12.8, p_20, p_60, p_100) and isophotc (c_160) in order to obtain an almost complete and simultaneous energy distribution. the apertures are 23arcsec (4.85 to 20 microns) and 99arcsec (60 and 100 microns), th truncated! [truncated!, Please see actual data for full text]